The uterus-like mass (ULM) is a tumorlike anatomical entity originally described in the

ovary The ovary () is a gonad in the female reproductive system that produces ova; when released, an ovum travels through the fallopian tube/ oviduct into the uterus. There is an ovary on the left and the right side of the body. The ovaries are end ...

in 1981 and thereafter reported in several locations of the pelvis and abdominal cavity including

broad ligament The broad ligament of the uterus is the wide fold of peritoneum that connects the sides of the uterus to the walls and floor of the pelvis. Structure Subdivisions Contents The contents of the broad ligament include the following: * Reproduc ...

greater omentum Greater may refer to: *Greatness, the state of being great *Greater than, in inequality * ''Greater'' (film), a 2016 American film *Greater (flamingo), the oldest flamingo on record * "Greater" (song), by MercyMe, 2014 * Greater Bank, an Australi ...

cervix The cervix (: cervices) or cervix uteri is a dynamic fibromuscular sexual organ of the female reproductive system that connects the vagina with the uterine cavity. The human female cervix has been documented anatomically since at least the time ...

small intestine The small intestine or small bowel is an organ (anatomy), organ in the human gastrointestinal tract, gastrointestinal tract where most of the #Absorption, absorption of nutrients from food takes place. It lies between the stomach and large intes ...

mesentery In human anatomy, the mesentery is an Organ (anatomy), organ that attaches the intestines to the posterior abdominal wall, consisting of a double fold of the peritoneum. It helps (among other functions) in storing Adipose tissue, fat and allowi ...

and

conus medullaris The conus medullaris (Latin for "medullary cone") or conus terminalis is the tapered, lower end of the spinal cord. It occurs near lumbar vertebral levels 1 (L1) and 2 (L2), occasionally lower. The upper end of the conus medullaris is usually no ...

. Basically, it is represented by a miniature

uterus The uterus (from Latin ''uterus'', : uteri or uteruses) or womb () is the hollow organ, organ in the reproductive system of most female mammals, including humans, that accommodates the embryonic development, embryonic and prenatal development, f ...

comprising a

smooth muscle Smooth muscle is one of the three major types of vertebrate muscle tissue, the others being skeletal and cardiac muscle. It can also be found in invertebrates and is controlled by the autonomic nervous system. It is non- striated, so-called bec ...

wall lined by

endometrium The endometrium is the inner epithelium, epithelial layer, along with its mucous membrane, of the mammalian uterus. It has a basal layer and a functional layer: the basal layer contains stem cells which regenerate the functional layer. The funct ...

thus outlining a uterus anatomical structure. Some of the reported cases have been associated to

urinary tract The human urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressu ...

and internal genitalia malformations whereas others appeared as a solitary finding. The term endomyometriosis has also been applied to this lesion. Different

pathogenetic In pathology, pathogenesis is the process by which a disease or disorder develops. It can include factors which contribute not only to the onset of the disease or disorder, but also to its progression and maintenance. The word comes . Descripti ...

views have been suggested for this anomaly: a) a metaplastic change in

endometriosis Endometriosis is a disease in which Tissue (biology), tissue similar to the endometrium, the lining of the uterus, grows in other places in the body, outside the uterus. It occurs in women and a limited number of other female mammals. Endomet ...

foci bringing about smooth muscle

hyperplasia Hyperplasia (from ancient Greek ὑπέρ ''huper'' 'over' + πλάσις ''plasis'' 'formation'), or hypergenesis, is an enlargement of an organ or tissue caused by an increase in the amount of Tissue (biology), organic tissue that results from ...

; b) a

congenital A birth defect is an abnormal condition that is present at childbirth, birth, regardless of its cause. Birth defects may result in disability, disabilities that may be physical disability, physical, intellectual disability, intellectual, or dev ...

anomaly due to fusion defects of the

Müllerian ducts The paramesonephric ducts (or Müllerian ducts) are paired ducts of the embryo in the reproductive system of humans and other mammals that run down the lateral sides of the genital ridge and terminate at the sinus tubercle in the primitive urogen ...

; and c) a sub-coelomic transformation of the

mesenchyme Mesenchyme () is a type of loosely organized animal embryonic connective tissue of undifferentiated cells that give rise to most tissues, such as skin, blood, or bone. The interactions between mesenchyme and epithelium help to form nearly ever ...

. ULM has also been reported associated to

endometrial carcinoma Endometrial cancer is a cancer that arises from the endometrium (the lining of the uterus or womb). It is the result of the abnormal growth of cells that can invade or spread to other parts of the body. The first sign is most often vaginal ...

and

breast cancer Breast cancer is a cancer that develops from breast tissue. Signs of breast cancer may include a Breast lump, lump in the breast, a change in breast shape, dimpling of the skin, Milk-rejection sign, milk rejection, fluid coming from the nipp ...

. A clonal

chromosome deletion Chromosomal deletion syndromes result from Deletion (genetics), deletion of parts of chromosomes. Depending on the location, size, and whom the deletion is inherited from, there are a few known different variations of chromosome deletions. Chromoso ...

2p21 was found in endomyometriosis by Verhest et al. while Pai evidenced a strict relationship among ULM,

and elevated serum

CA125 CA1, CA-1, CA 1, or Ca.1 may refer to: Aircraft and other vehicles * Buhl CA-1 Airster, an American sports airplane * Caproni Ca.1 (1910), an experimental biplane of 1910 * Caproni Ca.1 (1914), a World War I bomber * Schneider CA1, the first ...

supporting the view of ULM being either hormone-dependent or a form of

. There have been reports of the finding of occurrence of endometriosis in leiomyomatosis peritonealis disseminata. More than 15 cases of ULM have been reported so far. A case of ULM was reported 22 years after total

hysterectomy Hysterectomy is the surgical removal of the uterus and cervix. Supracervical hysterectomy refers to removal of the uterus while the cervix is spared. These procedures may also involve removal of the ovaries (oophorectomy), fallopian tubes ( salpi ...

, another 17 years after. Abdominal pain and a palpable mass are among the main clinical findings. Anyway, the phenomenon of smooth muscle cell

metaplasia Metaplasia () is the transformation of a cell type to another cell type. The change from one type of cell to another may be part of a normal maturation process, or caused by some sort of abnormal stimulus. In simplistic terms, it is as if the ...

occurring in association with endometriosis (endomyometriosis), as well as of smooth muscle differentiation at endometrio-myometrial junction independently from actually engendering uterus-like configurations in several locations of the pelvis, have been pointed out by several authors. A magnetic resonance account of this lesion type has been provided by Menn et al.Menn KA, Qin L, Fedoriw G, Gillette ME, McCarthy S (2007). Uterus-like mass: MRI appearance of a very rare entity. JMRI 26(1):162-164.

Sources

Further reading